How the extended life of rapidly decaying particles supports the special theory of relativity

Delays in the decay of unstable particles provide evidence for time dilation

Physicists used the muon half-life measured in labs to predict how many should reach detectors on Earth's surface after their production in collisions between atmospheric molecules and cosmic rays. Higher detection rates were consistent with a longer half-life due to slower movement through time.

Collisions between cosmic rays and atmospheric particles dwarf particle accelerators

According to Einstein's model of gravity, confining immense energy into a sufficiently small region would warp space-time enough to create a black hole. If accelerators actually did create black holes, then trillions more would be produced daily in the atmosphere, where collisions are millions of times more energetic.

Supercollider particles lag behind light by just 10 feet after 14 minutes of travel

The circular shape of the Large Hadron Collider allows particles to be repeatedly accelerated and redirected via electromagnetic fields rather than building equivalent energy in a linear chamber hundreds of miles long. The latter would require 5 trillion D batteries to achieve equivalent near-light speeds.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Particle interactions follow rules related to specific quantum properties

Like a business whose purchased inventory matches sold inventory, physicists identified specific patterns across decades of particle accelerator data, which became new conservation laws for elementary particles. These laws help identify which particle decays are expected or forbidden.

Why it takes tens of thousands of years for light from the sun's core to reach its surface

Photons take about eight minutes to travel through empty space to Earth after leaving the sun's surface. However, traveling from the core to the surface involves these particles of light undergoing a random walk—scattering off charged particles deep in the sun like a pinball—causing a trip that is more than 200 times shorter to last as long as 170,000 years.

Particle accelerators detect subatomic particles using millions of sensors

Calorimeters measure the energy of particles. Tracking devices can measure momentum and charge from the trajectory of particles, which is determined by recording tiny electrical signals. Time-of-flight detectors provide particle velocities directly and particle mass indirectly, giving physicists a suite of properties to compare with those of known matter.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Tachyons are theoretical particles that travel through space faster than light

The equations of special relativity require these objects to possess imaginary mass, and they would travel faster the more energy is taken away from them. The existence of tachyons would necessitate an unknown form of matter and lead to paradoxes involving information that can hypothetically travel backward in time.

Special relativity shows how motion at high speeds reshapes time, space, and energy

Einstein’s 1905 special theory of relativity revealed that the speed of light is absolute in the universe, forcing time and space to vary with one's speed. This idea led to the famous equation E=mc2, which shows that mass and energy are interchangeable.

Leptons do not experience the strong nuclear force that binds quarks together

Particles like electrons can exist in isolation, enabling them to move more freely. Within circuits, this allows electrons to carry energy across wire surfaces quickly. Contrastingly, light created in the sun's core is delayed by a million years on its way to Earth due to collisions with free electrons.

A guide to building your own cloud chamber to observe cosmic rays

Using felt, alcohol, dry ice, and a clear container—such as a fish tank—you can create a region of supersaturated air that will cling to passing particles, forming trails of cloud-like droplets. Muons will create straight paths, alpha particles will leave thicker ones, and electrons or positrons will zigzag.

View summaries of the most common types of radioactive decay and their associated particles

The alpha particle has the strongest ability to ionize other atoms it strikes, but it also does not travel very far before colliding with something and being absorbed. Gamma particles—high-energy photons—do not interact with matter as easily and therefore possess the greatest penetrating power, though this also makes their ionizing potential the smallest.

The wave nature of matter can produce phenomena like negative time and retrocausality

Within quantum mechanics, matter simultaneously exists as both fixed particles and extended waves, allowing it to emerge across barriers—just as sound travels through walls—before it fully enters the obstacle. The resulting measurements can show that particles spent negative time within a barrier, with the future occurring before the past.

The finite speed of light means we can only perceive the world's past

When objects emit or reflect light, it takes time for the light to reach an observer and be detected. During the travel time, the object may have changed, limiting detections to describing the conditions of the object when the light was first emitted or reflected, before it was detected.

Scientists keep track of time via light absorbed by cesium and strontium atoms

These absorptions happen in cycles, where one second is defined as 9,192,631,770 cycles of cesium atom radiation. Strontium atoms can be used to make clocks that do not gain or lose a second in 15 billion years.

The graviton may be the last missing piece of the Standard Model

While the electromagnetic, strong nuclear, and weak nuclear forces can be explained through interactions with particles, gravity is instead best modeled through spacetime curvature. Discovering a quantum particle of gravity would unite the two pillars of modern physics—quantum mechanics and general relativity—toward developing a theory of everything.

A nuclear reactor's characteristic blue light is produced from superluminal particles

When light travels through water, its effective speed is 25% lower than its speed in a vacuum. Just as sound waves bunch up and produce a sonic boom when objects move faster than the speed of sound, particles moving faster than this reduced speed generate a shock wave of light, visible as a blue hue.

Light can be used to slow the motion of atoms

While photons possess energy, they also have momentum, which allows them to collide with other particles, much like billiard balls, thereby slowing them down and reducing their kinetic energy, or temperature. Using multiple lasers from different directions, particles can be cooled to within one degree of absolute zero.

Quantum mechanics-based technology may explain the Fermi paradox

It describes the discrepancy between the high likelihood of life beyond Earth given the vastness of the universe and the lack of evidence for such life, since extraterrestrial civilizations have not communicated with us. However, quantum communication—a more information-dense and effective method than classical means—requires massive receivers and very narrow signals, which would easily miss Earth, making a lack of signals expected.

Astronomical models suggest dark matter must be 'cold,' or slow-moving

Theories for what constitutes dark matter have ranged from slow, planet-sized objects to light subatomic particles that travel at high speeds. However, fast-moving candidates would quickly spread across the universe, preventing the gradual gathering of visible matter into the galaxies and galaxy clusters seen today through gravity.

The importance of the mesosphere, the coldest part of Earth's atmosphere

Atmospheric gases are dense enough in this region to begin burning up debris traveling toward Earth's surface, producing meteor showers, or shooting stars. Although we normally associate decreasing temperatures with increasing altitude, temperatures increase beyond the mesosphere layer due to the absorption of high-energy ultraviolet radiation and X-rays.

Why starquakes may explain various phenomena associated with neutron stars

Fast radio bursts—repeated millisecond-long pulses of enormous energy from neutron stars—are emitted with a timing that resembles the earthquakes and aftershocks seen on Earth when geological activity releases energy from within the planet. Although pulsars should gradually spin more slowly as they lose energy from emitting jets of radiation, sudden increases may result from interior matter moving during starquakes.

The Planck time is the smallest unit of time that could ever be theoretically measured

Equal to about 5.39 × 10⁻⁴³ seconds, the unit is derived from calculating how long it would take light to travel the Planck length—the smallest theoretically measurable length. Quantum physics allows events to occur on smaller timescales, making them undetectable and their order to lose meaning.

The Curies were buried in lead-lined coffins to contain their radioactive bodies

Their discoveries of polonium and radium involved ongoing exposure to radioactive materials before shielding technology was developed. Their notebooks, furniture, and other belongings remain radioactive today, requiring researchers to sign a waiver and wear protective clothing to access.

Where you are located in a gravitational field affects how quickly you age

The closer something is to the center of a massive object, the greater the strength of the massive object's gravitational field as a result of space-time being depressed more severely. Time passes more slowly the deeper an object is in this gravitational depression, meaning objects in the universe naturally seek to age more slowly.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

After her fellow cult members tried to kill her with an LSD-infused hamburger, one member of the Manson Family, the murderous cult led by Charles Manson, decided to testify against the group's leader.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.